Lewis acids are chemical species that can accept a pair of electrons to form a coordinate covalent bond. They are electron-deficient compounds that have an empty orbital available to accept an electron pair. Lewis acids are important in a variety of chemical reactions, including organic and inorganic synthesis, catalysis, and coordination chemistry. Common examples of Lewis acids include metal cations such as Al3+ and Fe3+, as well as non-metal compounds like boron trifluoride (BF3) and hydrogen chloride (HCl). Lewis acids play a crucial role in many industrial processes and are extensively studied in the field of chemistry.